import { MathUtils, Mesh, MeshBasicMaterial, Object3D } from 'three'
import { LightningStrike } from './LightningStrike.js'

/**
 * @fileoverview Lightning strike object generator
 *
 *
 * Usage
 *
 * const myStorm = new LightningStorm( paramsObject );
 * myStorm.position.set( ... );
 * scene.add( myStorm );
 * ...
 * myStorm.update( currentTime );
 *
 * The "currentTime" can only go forwards or be stopped.
 *
 *
 * LightningStorm parameters:
 *
 * @param {double} size Size of the storm. If no 'onRayPosition' parameter is defined, it means the side of the rectangle the storm covers.
 *
 * @param {double} minHeight Minimum height a ray can start at. If no 'onRayPosition' parameter is defined, it means the height above plane y = 0.
 *
 * @param {double} maxHeight Maximum height a ray can start at. If no 'onRayPosition' parameter is defined, it means the height above plane y = 0.
 *
 * @param {double} maxSlope The maximum inclination slope of a ray. If no 'onRayPosition' parameter is defined, it means the slope relative to plane y = 0.
 *
 * @param {integer} maxLightnings Greater than 0. The maximum number of simultaneous rays.
 *
 * @param {double} lightningMinPeriod minimum time between two consecutive rays.
 *
 * @param {double} lightningMaxPeriod maximum time between two consecutive rays.
 *
 * @param {double} lightningMinDuration The minimum time a ray can last.
 *
 * @param {double} lightningMaxDuration The maximum time a ray can last.
 *
 * @param {Object} lightningParameters The parameters for created rays. See LightningStrike (geometry)
 *
 * @param {Material} lightningMaterial The THREE.Material used for the created rays.
 *
 * @param {function} onRayPosition Optional callback with two Vector3 parameters (source, dest). You can set here the start and end points for each created ray, using the standard size, minHeight, etc parameters and other values in your algorithm.
 *
 * @param {function} onLightningDown This optional callback is called with one parameter (lightningStrike) when a ray ends propagating, so it has hit the ground.
 *
 *
 */

class LightningStorm extends Object3D {
    constructor(stormParams = {}) {
        super()

        this.isLightningStorm = true

        // Parameters

        this.stormParams = stormParams

        stormParams.size = stormParams.size !== undefined ? stormParams.size : 1000.0
        stormParams.minHeight = stormParams.minHeight !== undefined ? stormParams.minHeight : 80.0
        stormParams.maxHeight = stormParams.maxHeight !== undefined ? stormParams.maxHeight : 100.0
        stormParams.maxSlope = stormParams.maxSlope !== undefined ? stormParams.maxSlope : 1.1

        stormParams.maxLightnings = stormParams.maxLightnings !== undefined ? stormParams.maxLightnings : 3

        stormParams.lightningMinPeriod = stormParams.lightningMinPeriod !== undefined ? stormParams.lightningMinPeriod : 3.0
        stormParams.lightningMaxPeriod = stormParams.lightningMaxPeriod !== undefined ? stormParams.lightningMaxPeriod : 7.0

        stormParams.lightningMinDuration = stormParams.lightningMinDuration !== undefined ? stormParams.lightningMinDuration : 1.0
        stormParams.lightningMaxDuration = stormParams.lightningMaxDuration !== undefined ? stormParams.lightningMaxDuration : 2.5

        this.lightningParameters = LightningStrike.copyParameters(stormParams.lightningParameters, stormParams.lightningParameters)

        this.lightningParameters.isEternal = false

        this.lightningMaterial = stormParams.lightningMaterial !== undefined ? stormParams.lightningMaterial : new MeshBasicMaterial({ color: 0xb0ffff })

        if (stormParams.onRayPosition !== undefined) {
            this.onRayPosition = stormParams.onRayPosition
        } else {
            this.onRayPosition = function (source, dest) {
                dest.set((Math.random() - 0.5) * stormParams.size, 0, (Math.random() - 0.5) * stormParams.size)

                const height = MathUtils.lerp(stormParams.minHeight, stormParams.maxHeight, Math.random())

                source
                    .set(stormParams.maxSlope * (2 * Math.random() - 1), 1, stormParams.maxSlope * (2 * Math.random() - 1))
                    .multiplyScalar(height)
                    .add(dest)
            }
        }

        this.onLightningDown = stormParams.onLightningDown

        // Internal state

        this.inited = false
        this.nextLightningTime = 0
        this.lightningsMeshes = []
        this.deadLightningsMeshes = []

        for (let i = 0; i < this.stormParams.maxLightnings; i++) {
            const lightning = new LightningStrike(LightningStrike.copyParameters({}, this.lightningParameters))
            const mesh = new Mesh(lightning, this.lightningMaterial)
            this.deadLightningsMeshes.push(mesh)
        }
    }

    update(time) {
        if (!this.inited) {
            this.nextLightningTime = this.getNextLightningTime(time) * Math.random()
            this.inited = true
        }

        if (time >= this.nextLightningTime) {
            // Lightning creation

            const lightningMesh = this.deadLightningsMeshes.pop()

            if (lightningMesh) {
                const lightningParams1 = LightningStrike.copyParameters(lightningMesh.geometry.rayParameters, this.lightningParameters)

                lightningParams1.birthTime = time
                lightningParams1.deathTime = time + MathUtils.lerp(this.stormParams.lightningMinDuration, this.stormParams.lightningMaxDuration, Math.random())

                this.onRayPosition(lightningParams1.sourceOffset, lightningParams1.destOffset)

                lightningParams1.noiseSeed = Math.random()

                this.add(lightningMesh)

                this.lightningsMeshes.push(lightningMesh)
            }

            // Schedule next lightning
            this.nextLightningTime = this.getNextLightningTime(time)
        }

        let i = 0,
            il = this.lightningsMeshes.length

        while (i < il) {
            const mesh = this.lightningsMeshes[i]

            const lightning = mesh.geometry

            const prevState = lightning.state

            lightning.update(time)

            if (prevState === LightningStrike.RAY_PROPAGATING && lightning.state > prevState) {
                if (this.onLightningDown) {
                    this.onLightningDown(lightning)
                }
            }

            if (lightning.state === LightningStrike.RAY_EXTINGUISHED) {
                // Lightning is to be destroyed

                this.lightningsMeshes.splice(this.lightningsMeshes.indexOf(mesh), 1)

                this.deadLightningsMeshes.push(mesh)

                this.remove(mesh)

                il--
            } else {
                i++
            }
        }
    }

    getNextLightningTime(currentTime) {
        return (
            currentTime +
            MathUtils.lerp(this.stormParams.lightningMinPeriod, this.stormParams.lightningMaxPeriod, Math.random()) / (this.stormParams.maxLightnings + 1)
        )
    }

    copy(source, recursive) {
        super.copy(source, recursive)

        this.stormParams.size = source.stormParams.size
        this.stormParams.minHeight = source.stormParams.minHeight
        this.stormParams.maxHeight = source.stormParams.maxHeight
        this.stormParams.maxSlope = source.stormParams.maxSlope

        this.stormParams.maxLightnings = source.stormParams.maxLightnings

        this.stormParams.lightningMinPeriod = source.stormParams.lightningMinPeriod
        this.stormParams.lightningMaxPeriod = source.stormParams.lightningMaxPeriod

        this.stormParams.lightningMinDuration = source.stormParams.lightningMinDuration
        this.stormParams.lightningMaxDuration = source.stormParams.lightningMaxDuration

        this.lightningParameters = LightningStrike.copyParameters({}, source.lightningParameters)

        this.lightningMaterial = source.stormParams.lightningMaterial

        this.onLightningDown = source.onLightningDown

        return this
    }

    clone() {
        return new this.constructor(this.stormParams).copy(this)
    }
}

export { LightningStorm }
